講演情報
[I-OR05-02]Fontan循環における超低流速成分による停滞評価：4D flow MRI研究
○稲毛 章郎1,3,4, 水野 直和2, 吉敷 香菜子3, 佐藤 麻朝3, 齋藤 美香3, 嶋 侑里子3, 松村 雄3, 上田 知実3, 嘉川 忠博3, 松井 彦郎3 (1.日本赤十字社医療センター 小児科, 2.榊原記念病院 放射線科, 3.榊原記念病院 小児循環器内科, 4.東京女子医科大学附属病院 足立医療センター 放射線科)
キーワード：
4D flow MRI、Fontan circulation、very-low-velocity flow
Objective: Fontan circulation features slow venous flow, but its hemodynamic impact remains unclear. We assessed Fontan-pathway flow on 4D flow MRI, focusing on very-low-velocity components.
Methods: Ten post-Fontan patients (age, 18.1 ± 3.5 years; range, 13 ~ 25 years) underwent 4D flow MRI at the Sakakibara Heart Institute. Hemodynamics were analyzed using iTFlow (Cardio Flow Design, Japan). We quantified voxel volume with velocities ＜ 0.01 m/sec. The slow-flow fraction was defined as the voxel volume at ＜ 0.01 m/sec divided by the segmented Fontan-pathway (ROI) volume. Energy loss (EL) was standardized as mean EL/kinetic energy (KE) and mean EL/KE/volume. Wall shear stress (WSS), helicity, and vorticity were also evaluated.
Results: Slow-flow fraction ranged from 2.7% to 30.4% (median, ~9%) and increased as mean velocity decreased, supporting its use as a stasis marker. Mean WSS tended to be higher with lower slow-flow fraction. Standardized EL showed no consistent relationship with slow-flow fraction, suggesting contributions from local high-velocity jets and pathway geometry. Helicity and vorticity varied across patients and were not simply related to slow-flow amount, indicating complementary information on rotational and secondary flow.
Conclusions: Very-low-velocity quantification may characterize stasis in the Fontan pathway, whereas EL and vortex-related metrics reflect other geometry-dependent hemodynamic features.
Methods: Ten post-Fontan patients (age, 18.1 ± 3.5 years; range, 13 ~ 25 years) underwent 4D flow MRI at the Sakakibara Heart Institute. Hemodynamics were analyzed using iTFlow (Cardio Flow Design, Japan). We quantified voxel volume with velocities ＜ 0.01 m/sec. The slow-flow fraction was defined as the voxel volume at ＜ 0.01 m/sec divided by the segmented Fontan-pathway (ROI) volume. Energy loss (EL) was standardized as mean EL/kinetic energy (KE) and mean EL/KE/volume. Wall shear stress (WSS), helicity, and vorticity were also evaluated.
Results: Slow-flow fraction ranged from 2.7% to 30.4% (median, ~9%) and increased as mean velocity decreased, supporting its use as a stasis marker. Mean WSS tended to be higher with lower slow-flow fraction. Standardized EL showed no consistent relationship with slow-flow fraction, suggesting contributions from local high-velocity jets and pathway geometry. Helicity and vorticity varied across patients and were not simply related to slow-flow amount, indicating complementary information on rotational and secondary flow.
Conclusions: Very-low-velocity quantification may characterize stasis in the Fontan pathway, whereas EL and vortex-related metrics reflect other geometry-dependent hemodynamic features.